Cable television is typically provided by delivering digital television programming through a community access television (CATV) system to subscribers. Specifically, in delivering the digital television programming, a headend in the CATV system distributes program data streams containing program materials through different channels of a distribution network, which occupy specified frequency bands. The program data stream for each channel is used to modulate a carrier associated with the channel. The resulting modulated carriers are combined and transmitted through the distribution network to a service area node, where the combined modulated carries are provided to a neighborhood. A subscriber in the neighborhood utilizes a set-top terminal to receive the combined modulated carriers and tune to a desired channel to obtain the program material from the associated modulated carrier.
In prior art, the combined modulated carriers provided to a neighborhood contain program materials of all channels used in a CATV system. However, as a cable TV provider uses an increasing number of channels to deliver additional program materials to attain a larger subscription, the number of available channels will soon run out. Thus, an urgent need arises where an efficient utilization of the limited bandwidth of the distribution network is required to deliver the additional program materials.